Gravel or Garnet for the under bedding?

Does it matter which gravel material I use under Pyrolox or Filox and calcite filter media?

One dealer feels 1/8 x 1/4 gravel or 8 â€“ 12 mesh garnet will work just fine under Filox or calcite.
The dealer outside town said I must use #8 garnet under Pyrolox, and I may not need anything under the calcite as my filters are small, (10â€ dia.) He feels 1/8 x 1/4 gravel is for water softeners.
Both dealers will sell me whatever I want at about the same price.

Is there something like a â€œBest Practiceâ€ when it comes to under bed materials?

I had read that garnet was a good bit heavier than gravel. When looking at the materials, garnet was the size of BB’s and gravel was various sizes and much larger overall.

The first dealer also suggested that I change the bottle size of my iron filter from 40x10 to 48x9. He had concerns that I may not be able to backwash the media correctly with the larger tank. I measured the water flow from an outside faucet. When the pressure at the water tank settles down to about 40 psi, I get about 11 Â½ GPM. He feels I need no less than 15 with the 10” tank and 1cf. Pyrolox or Filox.

Pyrolox is very heavy mineral so the higher gpm for backwash the better but... your filter will have a built in DLFC (drain line flow control) that will be selected based on the size of the tank which limits the flow. Ten gpm is the highest I've seen and in some instances based on what control valve you have, you can't get the internal DLFC so you have to go with an external flow control, usually Dole.

If it were me, I wouldn't us Pyrolox. There are other ways of treating for the same things that Pyrolox is used for; iron, manganese and H2S gas removal.

BTW, backwash is meant to lift/expand the bed and a 10" tank is used for more than 1.0 cuft of mineral where a 9" is for 1.0, so the more mineral, or the deeper the bed (tall and narrow means deeper bed), is going to require a higher flow rate. You shouldn't be designing your filter or specking replacement mineral, let that up to who you buy it from but I'd still use gravel because it is hard to beat.

These filters were already installed when I bought the place in 1996. They were working OK to my way of thinking when I took them apart. Orange water comes in, clear water goes out.
I started off just trying to do maintenance on them. I had read that the filter media is only good for 5 to 10 years, and I am way past that, plus I needed to replace the piston shaft seals again.
My local hardware says the valves are brass knockoffs of a Fleck 1â€ valve and those are the parts they sell me when they leak.
The very first time I worked on the iron filter, I lost the drain line flow control washer or it was missing. The folks at the hardware said I was better off without it, but replaced the washer in the ph filter drain fitting with a 7GPM washer. Thatâ€™s the way it has been for the last 10 or 12 years.
My hardware folks are retired to Florida and I now have a big box â€œmade in chinaâ€ hardware store in its place. Progress I guess.
Gary, give me some other types of filters I can use on the iron and manganese to research. I admit I am just guessing that I have a Pyrolox/Filox filter. I had very little to go on. The first filter is marked 1â€™ calcite, the second, 1â€™ mang dioxide in Magic Marker. Greensand uses chemicals, birm is light weight, 100lbs or so. This filter drained is much heavier than the calcite filter full, maybe 200lbs.
My gut tells me to just replace the media, gravel and seals and move on. My dealers think Fleck 7000 electronic plastic valves would do a better job for me than my old clock type valves.
Any suggestions?

It sounds as if you have the brass 2500, an excellent control valve. And manganese dioxide is Pyrolox. The 2500 is the same as t he 2510 and uses the same seals and piston etc.. Ya can't wear them out so the best choice is to replace the parts and buy the Pyrolox (2 50lb bags) and new gravel and things should work like they have for all these years.

There is no knock off of 1500/2500/2510 control valves. The Fleck 1" 2750 is brass and the big brother of the 3/4" 1500/2500/2510. The 2510 has the option of a 1" by pass valve in SS or plastic but internally it is a 3/4" valve.

Thanks Gary, I will follow your advice, gravel, media, and seals it will be. I will pick those items up first thing in the morning.
That will make the war department happy. She dislikes the taste of the tap water without the iron and ph filter, and refuses to drink the RO water except in coffee or ice cubes.